Initialize the test environment in Dev Container, allow running Docker tests from there

.devcontainer/Dockerfile

@@ -12,4 +12,4 @@ RUN apt-get update \
 WORKDIR /workspaces/python-wiremock
 COPY pyproject.toml uv.lock ./
 ENV UV_PROJECT_ENVIRONMENT=/usr/local
-RUN uv sync --frozen
+RUN uv sync --frozen --extra testing

.devcontainer/devcontainer-lock.json

@@ -0,0 +1,9 @@
+{
+  "features": {
+    "ghcr.io/devcontainers/features/docker-in-docker:4.1.2": {
+      "version": "4.1.2",
+      "resolved": "ghcr.io/devcontainers/features/docker-in-docker@sha256:ad3d6d36d95ee7f880f61f98862257f3e70253d3faef09f86af42fb87ee60429",
+      "integrity": "sha256:ad3d6d36d95ee7f880f61f98862257f3e70253d3faef09f86af42fb87ee60429"
+    }
+  }
+}

.devcontainer/devcontainer.json

@@ -4,6 +4,12 @@
 		"dockerfile": "Dockerfile",
 		"context": ".."
 	},
+	"features": {
+		"ghcr.io/devcontainers/features/docker-in-docker:4.1.2": {
+			"version": "latest",
+			"moby": false
+		}
+	},
 	"overrideCommand": true,
 	"customizations": {
 		"vscode": {
@@ -13,4 +19,4 @@
 			]
 		}
 	}
-}
+}

docs/CONTRIBUTING.md

@@ -46,13 +46,26 @@ file in the directory.
 When adding new examples,
 make sure to update the [documentation site page](./examples.md) too.
 
+## Testing
+
+To run tests in the Dev Container, just invoke the test scripts in the root directory:
+
+```shell
+sh run_tests.sh
+```
+
+For local developer environments, you may also need to run `uv sync --extra testing` 
+to get all the test modules installed.
+
+
 ## Working on Documentation
 
 The documentation is powered by [MkDocs](https://www.mkdocs.org/) and [ReadTheDocs](https://readthedocs.org/).
 All the necessary dependencies are included into the pyproject definition.
 To build the docs locally:
 
 ```bash
+cd docs
 uv run mkdocs build --site-dir=html
 ```
 

run_tests.sh

@@ -1,4 +1,11 @@
 #!/bin/sh
 
 rm -Rf build/ dist/ wiremock.egg-info coverage/ wiremock/tests/coverage/ html/ || true
-uv run pytest --cov=wiremock --tb=short
+# Container tests need a Docker daemon.
+if docker info >/dev/null 2>&1; then
+    set --
+else
+    echo "Docker not available, skipping tests/test_containers.py"
+    set -- --ignore=tests/test_containers.py
+fi
+uv run pytest tests/ --cov=wiremock --tb=short "$@"